Economic growth threatens to bring herbicide overuse to Asia

STANFORD -- Asia's economic growth is dramatically changing the region's
agriculture as people rise out of poverty, said experts who attended an
international conference on rice farming March 28-30 at Stanford University.

Asian farmers are finding it increasingly difficult to hire workers to
transplant and weed rice by hand as their national economies create
better-paying industrial jobs, conference participants said. The result is
that farmers in some regions are rapidly switching to a less labor- intensive
form of rice farming that greatly increases their dependence on herbicides.

Meanwhile, international research efforts are under way to produce rice
varieties that can stay ahead of the growing demand for rice, and those
varieties are direct-seeded, rather than transplanted, varieties, which will
further encourage farmers to use herbicides.

But herbicides, if used without enough understanding of the mostly
tropical eco-systems into which they are being introduced, could lead to
future reductions in rice yields as well as cause damage to human health and
the environment, said those attending the conference - an international group
of economists, plant breeders, agronomists, ecologists, epidemiologists and
managers from public research institutions, private agri-chemical companies
and academia.

"It's very clear now that if you use a single herbicide over time, you
build up resistance in weeds to that herbicide, and you can actually have a
yield loss," instead of a gain, said Stanford University economist Rosamond
Naylor, who organized the conference, which was sponsored by the Rockefeller
Foundation.

"We could go down the same chemical path with herbicides that we went down
earlier with insecticides," said Naylor, a research fellow with Stanford's
Institute for International Studies. The institute's researchers focus on
land use change and biotechnology transfer to developing countries, as well
as market-based incentives for pollution abatement and environmental
regulation. Naylor co-chaired the conference with Walter Falcon, director of
the Stanford institute and Donald Kennedy, Stanford president emeritus, who
directs the institute's environmental policy program.

Overuse of antibiotics

A similar path also was taken with overuse of antibiotics and has led to
increasing disease resistance to them, said Stanford biologist Paul Ehrlich.
"The huge price advantage farmers see at first from using herbicides will go
down," he predicted, as more and more weeds develop resistance.

Approximately 4.9 tons of rice per hectare are produced in Asia on 70
million hectares of irrigated land. To keep up with projected demand, the
yield per hectare must increase to 8 tons per hectare in the next 30 years,
conference participants said.

"The trick is to find a few easy principles that farmers can follow," said
Ken Fischer, director of research for the International Rice Research
Institute in Manila, Philippines. "The simple rule in the case of
insecticides is 'don't spray in the next 40 days' " after planting, he said.
The rule comes from research that indicated there is a high chance of killing
insect predators with early spraying.

Herbicide use has spread rapidly with direct seeding of rice, Naylor said.
"Grass weeds germinate at the same time as direct-seeded rice and look very
much like the rice, which makes hand weeding nearly impossible. Herbicides
that are selected specifically for weeds and that are not harmful to rice are
therefore essential to grow direct-seeded varieties," said Naylor, who has
studied rice production and labor practices in Indonesia and the Philippines.

"The combination of direct-seeded rice and herbicides enables farmers to
reduce their labor inputs by as much as 50 percent."

Much of the production gain in rice in Asia during the past 25 years has
come from continuous cropping and less crop rotation, she said, which means
less opportunity to break pest cycles, and there is also no wintertime fallow
to break cycles as in more temperate climates. In integrated insecticide
management programs, farmers are taught to use crop rotation and biological
predators as substitutes for insecticides. Similar strategies are now needed
for weed control, Naylor said.

Conference participants generally agreed that herbicides are less toxic
than insecticides, but many also noted that they have been found to
infiltrate groundwater and cause fish kills in the United States besides
creating health problems for some people who come into intense contact with
them. There is virtually no monitoring of health and environmental damage
from pesticides in most Asian countries, participants said.

Capital markets, training programs and environmental taxes or regulations
could be designed to encourage judicious use of herbicides, said Stanford
economist Larry Goulder, but that first requires more research to better
understand the ecology of weeds and the on-farm and off-farm costs of
herbicide use.

The conference produced a consensus for the need to undertake three types
of research:

Measurement of human health and environmental impacts from herbicides in
at least one intensively farmed region. This would permit some estimations of
herbicides' off-farm costs, which then could be used to design regulations or
taxes on them.

Ecological research into plant eco-systems to better understand weed
resistance and competition in rice farming as well as biological control
methods for weeds that could be used as part of an integrated weed management
program.

Research on how to more quickly transfer farming knowledge to millions
of small rice farmers. Although educational extension services have offered
training in integrated insect management to farmers in some areas of Asia,
Naylor and others said, the vast majority of Asian farmers have yet to
receive training, and adding weed control to the program will require
transferring even more knowledge.

The conference participants also recommended the following policy changes
be considered by international agencies and the national governments
affected:

Invest more in training and education of farmers because future yield
gains in rice will depend increasingly on information-intensive practices.

Consider an international labeling system for all types of pesticides so
that it is easier to monitor them and train people in their use.
Representatives of chemical companies present at the conference suggested
this because there are sometimes hundreds of brand names for a single
chemical on the market in Asian countries, they said.

Consider taxes and regulatory policies that take into account the
long-term and off-farm costs of herbicide use, once those costs have been
more clearly identified.

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